Physical: any problem that relates to the nervous system or to circulation could cause erectile dysfunction, e.g. the narrowing of blood vessels leading to the penis (as a result of high blood pressure, high cholesterol, diabetes, or other factors), an injury or as a result of surgery. Changes in hormone levels can also cause ED.

It is also possible for some medicines to cause erectile dysfunction.

You might find that you sometimes experience difficulty getting an erection and other times find it very easy. For example, you might get an erection in the morning and when you masturbate, but not when you try to have sex with your partner. In this type of scenario, it is likely that the cause of your erectile dysfunction is psychological. It could be stress related, for example. If you can’t ever get an erection, under any circumstances, the causes of your impotence are probably physical.